Specifying grid.layout in ggplot to anchor 4 plots in a 2x2 plot
I am having trouble specifying the dimensions of the grid layout in ggplot to fix four plots in a 2x2 plot (2 columns, 2 rows). I have an R code that inserts the first 2 plots on one line and the 3rd and 4th plots on separate lines (3 lines total) as shown in the image below. 
... This graph was generated using this simple R-code example:
setwd("...")
library(ggplot2)
library(grid)
x1 <- c(seq(1,20,1))
y1 <- c(seq(50,69,1))
df <- data.frame(x1,y1)
df$DOSE[df$x1<= 10] <- "50 mg"
df$DOSE[df$x1 > 10] <- "100 mg"
filename <- "test_plot.png"
png(filename, width=700, height=900, pointsize=14)
#4 ggplot2 graphs in a grid layout
vplayout <- function(x, y) viewport(layout.pos.row = x, layout.pos.col = y)
grid.newpage()
pushViewport(viewport(layout = grid.layout(4,4)))
#Plot 1
plotobj1 <- NULL
plotobj1 <- ggplot(data=df)
plotobj1 <- plotobj1 + geom_point(aes(x=x1, y=y1,colour=DOSE), shape=1, size=3)
plotobj1 <- plotobj1 + theme(legend.position="none")
print(plotobj1, vp=vplayout(1:2,1:2))
#Plot 2
plotobj2 <- NULL
plotobj2 <- ggplot(df)
plotobj2 <- plotobj2 + geom_point(aes(x=x1, y=y1,colour=DOSE), shape=1, size=3)
plotobj2 <- plotobj2 + theme(legend.position="none")
print(plotobj2, vp=vplayout(1:2,3:4))
#Plot 3
plotobj3 <- NULL
plotobj3 <- ggplot(df)
plotobj3 <- plotobj3 + geom_point(aes(x=x1, y=y1, colour=DOSE), shape=1, size=3)
plotobj3 <- plotobj3 + scale_colour_brewer(name="Dose", palette="Set1")
print(plotobj3, vp=vplayout(3,2:4))
#Plot 4 CWRES vs PRED
plotobj4 <- NULL
plotobj4 <- ggplot(df)
plotobj4 <- plotobj4 + geom_point(aes(x=x1, y=y1, colour=DOSE), shape=1, size=3)
plotobj4 <- plotobj4 + scale_colour_brewer(name="Dose", palette="Set1")
print(plotobj4, vp=vplayout(4,2:4))
dev.off()
I am having problems resizing and positioning positions. I want to have 3rd and 4th plots in one line (similar to the first two plots), so I have a small plot acceptable for posting.
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Although you can also use the above function grid.arrange
and multiplot
of cookbook-r.com, your code may also work. However, you find it difficult to do this by specifying a 4 by 4 grid, whereas all you need is a 2 by 2. And by the way, you don't need to create a NULL object first, so I removed those lines.
library(ggplot2)
library(grid)
x1 <- c(seq(1,20,1))
y1 <- c(seq(50,69,1))
df <- data.frame(x1,y1)
df$DOSE[df$x1<= 10] <- "50 mg"
df$DOSE[df$x1 > 10] <- "100 mg"
filename <- "test_plot.png"
png(filename, width=700, height=900, pointsize=14)
#4 ggplot2 graphs in a grid layout
vplayout <- function(x, y) viewport(layout.pos.row = x, layout.pos.col = y)
grid.newpage()
pushViewport(viewport(layout = grid.layout(2,2)))
#Plot 1
plotobj1 <- ggplot(data=df)
plotobj1 <- plotobj1 + geom_point(aes(x=x1, y=y1,colour=DOSE), shape=1, size=3)
plotobj1 <- plotobj1 + theme(legend.position="none")
print(plotobj1, vp=vplayout(1,1))
#Plot 2
plotobj2 <- ggplot(df)
plotobj2 <- plotobj2 + geom_point(aes(x=x1, y=y1,colour=DOSE), shape=1, size=3)
plotobj2 <- plotobj2 + theme(legend.position="none")
print(plotobj2, vp=vplayout(1,2))
#Plot 3
plotobj3 <- ggplot(df)
plotobj3 <- plotobj3 + geom_point(aes(x=x1, y=y1, colour=DOSE), shape=1, size=3)
plotobj3 <- plotobj3 + scale_colour_brewer(name="Dose", palette="Set1")
print(plotobj3, vp=vplayout(2,1))
#Plot 4 CWRES vs PRED
plotobj4 <- ggplot(df)
plotobj4 <- plotobj4 + geom_point(aes(x=x1, y=y1, colour=DOSE), shape=1, size=3)
plotobj4 <- plotobj4 + scale_colour_brewer(name="Dose", palette="Set1")
print(plotobj4, vp=vplayout(2,2))
dev.off()
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